加载资源失败:服务器响应状态为500(内部服务器错误)MVC JAVASCRIPT

我试图从JavaScript视图到控制器发布2个参数，但我得到这个错误。不知道为什么…Failed to load resource: the server responded with a status of 500 (Internal Server Error)

transfer.js $(document).ready(function () { $("#transferPlayerButton").click(function () {

    var playerId = document.getElementById("id_player").value;
    var teamId = document.getElementById("id_team").value;
    $.ajax({
        type: 'post',
        url: '/Player/TransferPlayer',
        data:
            {
                playerId: playerId,
                newTeamId: teamId
            },
        contentType: 'application/json;charset=utf-8',
        dataType: 'json',
        success: function (data) {
            alert("Success!");
        }

    });
});

});

    [HttpPost]
    public ActionResult TransferPlayer(int playerId, int newTeamId)
    {
        return Content(string.Format("Player {0} it is now at team {1}.", playerId, newTeamId)); 
    }

，这是我的观点。我已经映射对象到数据库对象，但我能弄清楚为什么我得到这个500错误。需要一些帮助。我是mvc/javascript的新手

  @model FotballTeamsProject.Models.PlayerModels.PlayerTransferModel

    <script src="@Url.Content("~/Scripts/Player/Transfer.js")"></script>
    <script type="text/javascript">
    var transferUrl= "@Url.Action("TransferPlayer", "Player")";
    </script>
    <table>
    <thead>
    <tr>
        <th>ID</th>
        <th>Nume</th>
        <th>Prenume</th>
        <th></th>
        <th>Skill</th>
        <th>Valoare</th>
        <th></th>
        <th>Echipa Actuala</th>
        <th style="margin-right: 10px;">Echipa Viitoare</th>
    </tr>
</thead>
<tbody>
        <tr>
            <td id="id_player">@Model.Player.id_player</td>
            <td>@Model.Player.player_firstname</td>
            <td>@Model.Player.player_surname</td>
            <td></td>
            <td>@Model.Player.player_skill</td>
            <td>@Model.Player.player_value</td>
            <td></td>
            <td>@Model.Player.name_team</td>
            <td style="text-align: right;">
                <select id="id_team">
                    <option selected="selected" value="0">Fara echipa</option>
                    @foreach (var teamInfo in Model.Teams)
                    {
                        <option value="@teamInfo.Key">@teamInfo.Value</option>
                    }
                </select>
            </td>
          </tr>
</table>
</tbody>
    <p>
        <input id="transferPlayerButton" type="button" value="Transfera" />
    </p>